Production of insolubilized protein artificial filamentary products



Patented Dec. 12, 1950 PRODUCTION OF INSOLUBILIZED PROTEIN ARTIFICIAL FILAMENTARY PRODUCTS Robin H. K. Thomson, Kilwinning, Scotland, assignor to Imperial Chemical Industries Limited, a corporation of Great Britain No Drawing. Application July 2, 1946, Serial No. 681,153. In Great Britain August 22, 1945 11 Claims.

The present invention relates to a new or improved method for insolubilising artificial filaments, threads, fibres and the like filamentary products spun from protein solutions, and more particularly those obtained by the spinning of solutions of vegetable seed globulins, for instance peanut protein, or phospho-proteins,-for instance casein, in aqueous alkaline or other suitable aqueous solvent media into suitable acidified saline coagulating baths. Sodium sulphate solutions slightly acidified with sulphuric acid are in practice most advantageously used as the coagulating baths.

The filamentary products emerging from the coagulating bath are still easily soluble in dilute saline solutions. They can be rendered insoluble in dilute saline solutions and in cold water by a hardening treatment with formaldehyde, but in order to render the filamentary products capable of ordinary textile application they must be rendered capable of withstanding also the action of boiling water, so that they can be dried off without sticking together, and further the action of hot dilute acid solutions such as are used in the application of acid wool dyes and of hot dilute alkaline solutions such as are used in laundering.

While a number of processes for insolubilisin protein artificial filamentary products for this purpose have been described it is believed that the best insolubilisation and the best physical properties and separation of the individual filamerits or the like from one another have hitherto been attained by the use of a strongly saline solution of formaldehyde containing not less than 30 parts sodium chloride per 100 parts water by weight, acidified with sufiicient hydrochloric acid or sulphuric acid to bring the pH below 1. Such a bath is described in U. S. Patent No. 2,347,677. The coagulating solution associated with the filamentsor the like emerging from the coagulating bath is usually rinsed away from them by treating them with sodium chloride brine before introducing them into the aforementioned insolubilising solution.

The insolubilisation with the aforesaid acidified brine formaldehyde solution however necessitates the maintenance of the filamentary product in We have now found that the insolubilisation of unhardened protein artificial filamentary products may be considerably accelerated and products of excellent physical properties having no appreciable tendency to clump together may be obtained if the filaments, fibres, threads or the like are first treated in an aqueous formaldehyde bath saturated to both sodium chloride and sodium sulphate or to both sodium chloride and magnesium sulphate, at a pH of 4 to 6 i. e. at a pH within the isoelectric range of the protein at a temperature not exceeding C. and are thereafter treated in an aqueous formaldehyde bath strongly acidified with sulphuric acid at a raised temperature, preferably between 55 C. and 0., this strongly acidified formaldehyde bath being saturated with sodium sulphate or magnesium sulphate at the temperature employed, preferably according as the former or the latter of these salts was used in the first mentioned of the two baths.

According to the present invention therefore the method of insolubilising artificial filamentary products obtained by the spinning of solutions of vegetable seed globulins, for instance peanut proteins, or phospho-proteins, for instance casein, in aqueous alkaline or other suitable aqueous solvent media into suitable acidified saline coagulating baths comprises treating the said filamentary products in an aqueous formaldehyde bath saturated to both sodium chloride and sodium sulphate or to both sodium chloride and magnesium sulphate at a pH of 4 to 6 and at a temperature not exceeding 60 C. and thereafter treating the filamentary products in an aqueous formaldehyde bath strongly acidified with sulphuric acid and saturated with sodium sulphate or magnesium sulphate at the temperature employed, the said strongly acidified formaldehyde bath being at a raised temperature.

Preferably if the formaldehyde bath of pH 4 to 6 is saturated to both sodium chloride and sodium sulphate then the strongly acidified formaldehyde bath is saturated with sodium sulphate while if the formaldehyde bath of pH 4 to 6 is saturated to both sodium chloride and magnesium sulphate then the strongly acidified formaldehyde bath is saturated with magnesium sulphate.

The formaldehyde concentrations in the two baths may be widely varied, but high concentrations are unnecessary. The time for which the filamentary products require to remain in contact with the formaldehyde bath at pH 4 to 6 saturated with sodium chloride and sodium or magnesium sulphate depends on the temperature at which this bath is used, and in the region of 50 C. a period of about five minutes is sufficient, or at about 40 C. about eight minutes to fifteen minutes. It is essential that this bath should be saturated both to sodium chloride and sodium sulphate, or sodium chloride and magnesium sulphate otherwise it is impossible to employ the subsequent strongly acidified bath at a temperature suificiently high to effect rapid insolubilisation without at the same time causing the filamentary products to clump together and yield products of inferior physical characteristics. In this strongly acidified bath the sulphuric acid concentration may advantageously range from about 175 grams sulphuric acid per litre upwards. Owing to the volatility of formaldehyde and the irritating nature of its vapour the temperature of this second bath preferably does not exceed 75 C. but it will be understood that the lower the temperature the less rapid is the insolubiisation A t 70 C. the time required is usually about to minutes.

The invention is illustrated by the following examples, in which the parts'are parts by Weight except where otherwise indicated.

Example 1 under tension through a saturated sodium chloride bath at approximately C. m which they remained until their. longitudinal contractility had been greatly reduced. The filaments were then cut into staple fibre and stored in a saturated sodium chloride solution having a pH value of '7 at room temperature until required.

The resulting unhardened staple fibre was immersed in a warm solution containing 1 per cent formaldehyde by weight, which solution had been saturated to sodium chloride and sodium sulphate and brought to pH 5.0, the temperature of the resulting bath being'50' C. 'After five minutes immersion the staple fibre was removed from this bath and allowed to drain somewhat.

It was then transferred to a bath consisting of a hot saturated sodium sulphate solution'containing 1% per cent formaldehyde by weight, to which solution had been added a fifth of its volume of concentrated sulphuric acid and sufficient solid sodium sulphate to keep the resulting bath saturated. The temperature of the bath was 70 C. and its sulphuric acid content was about 240 grams per litre. The bath has a pH value less than 1 when measured at room temperature. The staple fibre was left in this bath for ten minutes and was removed and washed. It opened well and was found to be unimpaired by boiling water. It also resisted the action of a bath simulating an acid wool dye bath and containing 0.1 per cent sulphuric acid and per cent sodium sulphate for 90 minutes at 97 C. without impairment of its handle and general characteristics. The fibre was then finished off in known manner by treating with a solution of Lissapol C (registered trade-mark) at C. for 1 hours and then in V2 per cent sodium carbonate solution. The fibre was found to be possessed of excellent characteristics for the production of textiles, and withstood laundering with slightly alkaline soap solutions satisfactorily.

Example 2 The unhardened filamentary material treated was the same as in Example 1, and the staple fibre was immersed for five minutes in a warm bath containing 1 per cent by weight of formaldehyde at pH 5 saturated by sodium chloride and sodium sulphate as described in Example 1, It was then transferred to a strongly acidified bath made up as described in Example 1 except that the volume of concentrated sulphuric acid used was only one eighth of that of the formaldehyde solution saturated with sodium sulphate. The fibre was left in this bath for fifteen minutes and was then removed and washed. Its properties were very similar to those of the insolubilisation staple fibre whose preparation is described in Example 1.

Example 3 The unhardened staple fibre employed was the same as that used according to Example 1. It was immersed in a warm solution containing 1 per cent formaldehyde by weight that had been saturated with sodium chloride and magnesium sulphate and brought to pH 5.0 the temperature of this solution being 50 C. After. five minutes immersion the staple fibre was removed from the bath and allowed to drain somewhat. It was then transferred to a bath consisting of a hot saturated magnesium sulphate solution containing 1 per cent formaldehyde by weight, to which solution had been added one quarter of its volume of concentrated sulphuric acid and sufiicient magnesium sulphate to keep the solution saturated. The temperature of the resulting bath was C. and its sulphuric acid content was 318 grams per litre. The bath has a pH value of less than 1 when measured at room temperature. The staple fibre was left in this bath for ten minutes and was then removed and washed. It opened well and was found to be unimpaired by boiling water. It also resisted the action of a bath containing 0.1 per cent sulphuric acid and per cent sodium sulphate at 97 C. for minutes without impairment of its form. It closely resembled the fibre produced according to Example 1 in it physical properties, handle and laundering resistance.

I claim:

1. A method of insolubilizing artificial filamentary products obtained by spinning aqueous, alkaline solutions of proteins into acidified saline coagulating baths which comprises treating the coagulated filamentary products, havin a solubility substantially the same as that immediately after coagulation, for up to about fifteen minutes, at a temperature not exceeding 60 C. with an aqueous, formaldehyde solution havin a pH of between about 4 to 6, which is saturated to both sodium chloride and a sulphate from the group consisting of sodium sulphate and mag nesium sulphate at said temperature, and immediately thereafter treating the resulting products at a temperature not exceeding 75 C. for up to about fifteen minutes in an aqueous formaldehyde solution containing at least grams per liter of sulphuric acid, which is saturated, at the treatment temperature, with a sulphate from the group consisting of sodium sulphate and magnesium sulphate.

2. A method as claimed in claim 1 wherein the strongly acidified formaldehyde bath employed is saturated with sodium sulphate When the formaldehyde bath of pH 4 to 6 is saturated to both sodium chloride and sodium sulphate.

3. A method as claimed in claim 1 wherein the strongly acidified formaldehyde bath employed is saturated with magnesium sulphate when the formaldehyde bath of pH 4 to 6 is saturated to both sodium chloride and magnesium sulphate.

4. A method as claimed in claim 1 wherein the filamentary products are kept in the formaldehyde bath at pH 4 to 6 for about 5 minutes in the region of 50 C.

5. A method as claimed in claim 1 wherein the filamentary products are kept in the formaldehyde bath at pH 4 to 6 for about eight to fifteen minutes at about 40 C.

6. A method as claimed in claim 1 wherein the filamentary products are kept in the strongly acidified formaldehyde bath for about 10 to minutes at 70 C.

7. Insolubilised artificial filamentary products when produced by the method claimed in claim 1.

8. A method of insolubilizing artificial filamentary products obtained by spinnin aqueous alkaline solutions of proteins into acidified saline coagulating baths which comprises treating the coagulated filamentary products, having a solubility substantially the same as that immediately after coagulation, in untensioned condition at a temperature between about 40 C. to 60 C. for

between about 5 to 15 minutes with an aqueous 3 formaldehyde solution having a pH between about 4 to 6 which is saturated, at the temperature of treatment, to both sodium chloride and a sulphate from the group consisting of sodium sulphate and magnesium sulphate, and immediately thereafter treating the resulting products in untensioned condition at a temperature between about C. to C. for between about 10 to 15 minutes in an aqueous formaldehyde solution containing between about grams to 318 grams per liter of sulphuric acid, which is saturated at the temperature of treatment, with a sulphate from the group consisting of sodium sulphate and magnesium sulphate.

9. A method as claimed in claim 1 wherein said protein is peanut protein.

10. A method a claimed in claim 1 wherein said filamentary products are in an untensioned condition during said formaldehyde bath treatments.

11. A method as claimed in claim 10 wherein said filamentary products are staple fibers.

ROBIN H. K. THOMSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,266,672 Wormell Dec. 16, 1941 2,347,677 Fieldsend et a1. May 2, 1944 2,372,622 Wormell Mar. 27, 1945 2,385,674 Wormell Sept. 25, 1945 FOREIGN PATENTS Number Country Date 107,262 Australia May 4, 1939 525,738 Great Britain Sept. 3, 1940 

1. A METHOD OF INSOLUBILIZING ARTIFICIAL FILAMENTARY PRODUCTS OBTAINED BY SPINNING AQUEOUS, ALKALINE SOLUTIONS OF PROTEINS INTO ACIDIFIED SALINE COAGULATING BATHS WHICH COMPRISES TREATING THE COAGULATED FILAMENTARY PRODUCTS, HAVING A SOLUILITY SUBSTANTIALLY THE SAME AS THAT IMMEDIATELY AFTER COAGULATION, FOR UP TO ABOUT FIFTEEN MINUTES, AT A TEMPERATURE NOT EXCEEDING 60*C. WITH AN AQUEOUS, FORMALDEHYDE SOLUTION HAVING A PH OF BETWEEN ABOUT 4 TO 6, WHICH IS SATURATED TO BOTH SODIUM CHLORIDE AND A SULPHATE FROM THE GROUP CONSISTING OF SODIUM SULPHATE AND MAGNESIUM SULPHATE AT SAID TEMPERATURE, A IMMEDIATELY THEREAFTER TREATING THE RESULTING PRODUCTS AT A TEMPERATURE NOT EXCEEDING 75*C. FOR UP TO ABOUT FIFTEEN MINUTES IN AN AQUEOUS FORMALDEHYDE SOLUTION CONTAINING AT LEAST 175 GRAMS HER LITER OF SULPHURIC ACID, WHICH IS SATURATED, AT THE TREATMENT TEMPERATURE, WITH A SULPHATE FROM THE GROUP CONSISTING OF SODIUM SULPHATE AND MAGNESIUM SULPHATE. 